Fully silicon ALED-photodiode optical data link module

Abstract

In a silicon-based light emitting diode-photodiode (LED-PD) arrangement, the LED is implemented as an avalanche LED (ALED) and the ALED and PD are integrated into a common integrated circuit. The ALED is formed around a cross-shaped PD and is separated from the PD by a deep trench region. In order to create current crowding close to the deep trench the ALED includes an NBL or PBL having a narrowing at its end.

1. An ALED-PD structure, comprising
 an avalanche light emitting diode (ALED), 
 a photo diode (PD) integrated as a single integrated circuit (IC), 
 wherein said ALED and PD are implemented in silicon, 
 also wherein said ALED also includes an anode and a cathode defining an avalanche breakdown junction between buried layers of the anode and cathode or between a buried layer and a sinker of the anode and cathode, 
 also wherein said photo diode (PD) includes an anode and a cathode in which the anode of the PD comprises a central anode defined by a p+ region formed in an n-epitaxial region, and 
 also wherein the cathode of the PD comprises multiple n+ regions formed around the anode of the PD. 
 
     
     
       2. An ALED-PD structure of  claim 1 , wherein the anode and cathode of the PD are laid out to define a cross, with a cross-shaped isolation region formed around the PD, the cross defining internal corners. 
     
     
       3. An ALED-PD structure of  claim 2 , wherein the cathode of the PD includes the n-epitaxial region and one or more n+ regions formed in the n-epitaxial region. 
     
     
       4. An ALED-PD structure of  claim 3 , wherein the anode of the PD includes a p-sinker (PS) extending below the p+ region of the PD. 
     
     
       5. An ALED-PD structure of  claim 1 , wherein the ALED-PD structure is formed as part of a CMOS or BiCMOS SOI process,
 also wherein any P or N type buried layers formed in the PD as part of the CMOS or BiCMOS SOI process are removed to leave the PD without any P or N Type buried layers, and 
 also wherein the ALED includes two anodes and two cathodes, each anode or cathode extending into an internal corner of the cross defined by the deep trench isolation (DTI). 
 
     
     
       6. An ALED-PD structure of  claim 1  wherein the buried layer of at least one of the anode and cathode of the ALED is configured to be narrowed toward its end defining the avalanche junction. 
     
     
       7. A method of forming a silicon ALED-PD structure, comprising
 forming the ALED and the PD as part of the same process in an integrated circuit, 
 wherein the ALED and PD are formed in a CMOS or BiCMOS SOI process, 
 also wherein the ALED is formed to extend around the PD, and 
 also wherein at least one ALED anode is formed of a first doping type and at least one ALED cathode is formed of a second doping type, each ALED anode and ALED cathode including a sinker of their doping type, and at least one of the ALED anode and ALED cathode including a buried layer of their doping type to define an avalanche breakdown region in the ALED between one of the buried layers of one doping type and a sinker or buried layer of the opposite doping type. 
 
     
     
       8. A method of  claim 7 , further comprising narrowing the ends of at least some of the buried layers to where, under normal operation, local avalanche breakdown takes place due to current crowding at the junction between one of the buried layers and a buried layer or sinker of opposite doping type. 
     
     
       9. A method of  claim 7 , further comprising separating the ALED from the PD by a cross-shaped deep trench isolation region defining four internal angles, and forming the ALED anodes and ALED cathodes in the internal angles.